1. Field of the Invention
The present invention relates generally to a method for recovering potable water which is safe for drinking from the exhaust of an internal combustion engine. More particularly, the present invention relates to a method which uses a liquid desiccant to extract from the exhaust of an internal combustion engine and then provides the desiccant to a reverse osmosis unit to extract potable water from the desiccant.
2. Description of the Related Art
Supplying potable water to military personnel on remote missions (especially in hot, dry, desert-like conditions) is a very difficult logistical problem. Unlike fuel or ammunition, water is continuously consumed by military personnel and water cannot be made lighter or less bulky.
The average daily consumption of drinking water for a Marine or soldier on is about 16 liters per person. A platoon of forty four servicemen will consume over 170 gallons of purified water a day. The weight of 170 gallons is approximately 1400 pounds. It is often very difficult to supply the replacement for this amount of water.
For troops which use motorized vehicles (such as the high mobility multipurpose wheeled vehicle (HMMWV)), the water generated by the combustion of fuel can provide all or part of a serviceman's daily requirement of drinking water. A typical internal combustion engine produces a gallon of water for gallon of fuel the engine burns.
The United States Army developed a Water Recovery Utilizing Exhaust (WRUE) system which uses refrigeration coils to condense the water in engine exhaust. The WRUE system requires a mechanical refrigeration unit for the cooling cools and a series of filters and other water treatment steps to remove particulates and organic materials from the condensate. An engine powered compressor pressurizes a gaseous refrigerant. The pressurized refrigerant gas enters a heat exchanger/condenser where the gas is condensed to a liquid state. The liquid then passes through an expansion device and enters an evaporator. In the evaporator, the evaporating refrigerant absorbs heat from the engine exhaust gases changing the liquid refrigerant back to a gas. The evaporating liquid cools the engine exhaust to a temperature below the dew point of water. The condensed water is collected in a pan at the bottom of the evaporator. The liquid water from the evaporator is periodically pumped through a particle filter to remove soot and other particles, then through an activated carbon filter to remove any unburned hydrocarbons. A disinfectant, such as hypochlorite, is added to the water to make the water safe to drink. The WRUE system is mechanically complex, expensive, and uses a significant amount in the cargo area of a HMMWV. The power required to run the compressor can also significantly reduce the fuel economy in the vehicle.